JP3859455B2 - Semiconductor laser pumped solid-state laser device and state diagnosis method of the device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor laser pumped solid-state laser device and a state diagnosis method for the device, and in particular, a highly reliable semiconductor laser pumped solid-state laser device that can easily and easily perform deterioration diagnosis of a semiconductor laser and the state of the device. It relates to a diagnostic method.
[0002]
[Prior art]
As a pumping method using light of a solid-state laser medium such as Nd: YAG, a semiconductor laser diode (hereinafter referred to as LD) having a higher absorption efficiency into the laser medium than a lamp and having a small size, high efficiency, and long life is used as an excitation light source. In recent years, so-called LD-pumped solid-state lasers have attracted attention. In particular, recently, an LD-pumped solid-state laser device has been developed that uses several hundreds of LDs in one resonator to emit laser output up to kilowatts.
[0003]
LD is said to have a life of 10 times longer than that of a lamp and can be used continuously for about 10,000 hours. However, this time is average, and there are some individual LDs whose output drops in about several thousand hours, and it is difficult to completely recognize and remove them by initial LD selection. Also, even when the LD is mounted on a solid-state laser device, the life is significantly shortened by disturbances such as static electricity, electrical surges from the power supply, return light, dust, gas, condensation, etc. and the external environment. In order to improve the reliability of the apparatus and deal with early failure, it is necessary to detect the amount of excitation light from the LD by some means and grasp the degree of deterioration.
[0004]
Therefore, in a low-power operating LD of 10 W or less, an excitation light that slightly leaks from a highly reflective surface (back surface) opposite to the emission surface (front surface) of an ordinary LD chip is usually detected by a photodetector arranged in the LD package. The energy is detected and used for controlling the amount of excitation light or detecting the deterioration of the LD.
[0005]
In addition, the laser beam emitted from the output mirror constituting the solid-state laser resonator to the outside of the resonator is partially branched, or the energy of the oscillating light leaking from mirrors other than the output mirror is measured with a photodetector. Therefore, methods used for laser output control and LD degradation detection are also used.
[0006]
There has also been proposed a method for detecting the fluorescence intensity or the fluorescence distribution in a direction along the laser oscillation optical axis or on an extension line thereof. FIGS. 15 and 16 show an embodiment described in Japanese Patent Application Laid-Open No. 2000-269576, in which fluorescence emitted from a solid laser rod along the laser oscillation optical axis is branched by a monitor mirror, and is scanned by a CCD camera. A method has been proposed in which the excitation distribution is imaged and observed, and the drive current of each LD is independently adjusted in order to make the excitation distribution uniform from the image. This prior art will be described below.
[0007]
In this conventional example, as shown in FIG. 16, when setting the values of the drive currents of the LDs 102 to 107, excitation is first performed with the mirror of the solid-state laser resonator removed, so that the excitation distribution becomes uniform. Describes a method of attaching a resonator mirror again after adjusting with variable resistors 122 to 127 while observing an excitation distribution with a CCD camera 130. Further, as shown in FIG. 15, with the resonator mirrors 120 and 121 attached, a folding mirror 128 is inserted into the resonator only at the time of fluorescence distribution measurement, and the fluorescence from the laser rod 101 is passed through the folding mirror 128 to the CCD. A method of observing with the camera 130 has also been proposed.
[0008]
Further, in this conventional example, as a method of downsizing the LD driving power source 117, simplifying the wiring, and adjusting the driving currents of the LDs 102 to 107 independently, all the LDs are connected in series and one power source 117 is connected. In which the variable resistors 122 to 127 are connected in parallel to the LDs 102 to 107 to control the current value flowing through the LDs.
[0009]
[Problems to be solved by the invention]
However, since the LD chip for high output operation of 20 W or more that is currently popular has a light emitting surface of about 1 cm in length, in order to detect all light of 1 cm width with a photodetector provided behind Since a wide detector is required and the amount of light leaking from the back surface of the chip is large, the output of the photodetector will be saturated unless a light reduction filter is provided in front of the photodetector. For this reason, the configuration of light detection becomes complicated and the cost increases. Therefore, the LD for high-power operation usually does not have a mechanism for detecting the amount of light in the package itself. Further, in the case of a configuration called stacking, in which LDs are stacked in a direction perpendicular to the semiconductor layer at a narrow interval, there is not a sufficient place for providing a photodetector on the back surface, so that a photodetection function is not usually provided. . For this reason, in the case of a high-power solid-state laser device using a high-power LD, it is impossible to directly detect the deterioration of the LD.
[0010]
In addition, the light output capable of stably operating the LD element having a light emitting surface length of about 1 cm is about 20 W to a maximum of about 80 W. Therefore, in the case of a high-power laser device that requires higher excitation, it is necessary to use a plurality of LDs. For example, in order to obtain a laser output of a kilowatt class from a solid-state laser device, several tens to hundreds or more LDs may be used as a pumping source for one solid-state laser medium. In the case of using these simultaneously, if each LD element is provided with an independent drive power supply, the number of power supplies becomes very large, a large installation volume is required, wiring is complicated, and operation efficiency is poor. Thus, it is usual to drive several LDs of several to several tens as a group, electrically connected in series.
[0011]
When a large number of LDs are driven in series in this way, even if a light detection function is provided for each LD, and a decrease in output of a specific LD can be detected thereby, a plurality of LDs are electrically connected in series. Therefore, it is impossible to increase the drive current of only a specific LD to compensate for the output drop of only that LD. For example, when the output of a specific LD is compensated by increasing the drive current, the output of many other LDs that do not cause a decrease in output increases from the original value, so that the pump light output is greatly increased for the entire group. The solid-state laser output also increases far beyond the initially set value, the balance of excitation with the LDs of other groups is lost, and the solid-state laser output decreases or becomes unstable. The quality of the beam may be degraded. Further, when a photodetector is provided in several tens or more of individual LDs, wiring and circuits for controlling them are very complicated, and the cost of the apparatus is increased.
[0012]
Further, as a conventionally known method, it is possible to detect the amount of laser oscillation extracted outside the solid-state laser resonator and know the degree of degradation of the LD indirectly. However, the amount of oscillation light from the resonator not only decreases due to the deterioration of the LD, but also significantly decreases due to misalignment of the resonator mirror, contamination and damage of the mirror itself, alteration and damage of the laser medium, and contamination of the coating film. However, since the cause other than LD is higher in frequency, it is difficult to grasp the degree of deterioration of the LD separately from the amount of laser oscillation light.
[0013]
In the conventional method shown in FIGS. 15 and 16, the fluorescence distribution becomes invisible due to the necessity of installing a CCD camera along or on the extension of the laser optical axis and the influence of strong laser light when laser oscillation is performed. Therefore, when measuring the fluorescence distribution, it is necessary to remove one end of the resonator mirror or temporarily insert a folding mirror into the resonator to prevent oscillation as a solid-state laser device. Since the deterioration of LD cannot be detected, it is not practical. In addition, when a plurality of laser rods are arranged in the laser device for the purpose of obtaining a high laser output, a long laser rod with one CCD camera from one direction along the laser oscillation optical axis, or a plurality of laser rods It is extremely difficult to observe the fluorescence distribution in the laser rod at once because of the focal length of imaging, so multiple CCDs, multiple folding mirrors, and imaging lenses with various focal lengths are required. As a result, the optical system becomes extremely complicated and expensive.
[0014]
Furthermore, as shown in the conventional diagram, when all the LDs are connected in series and driven by a single power source, the number of LDs connected in series exceeds 20 to 30 and the drive voltage exceeds 40V. Conversely, the power supply becomes very large. This is particularly because the electronic components constituting the power supply corresponding to the increase in driving voltage are suddenly increased in size. When there are a large number of mounted LDs, 20 to 30 LDs are grouped into a power supply. If you divide, the overall power supply becomes smaller. Also, when handling a large current and high voltage with a single power supply, the cooling method, durability, and reliability of electronic components are reduced, and the difficulty of replacement and maintenance due to the enlargement of individual components is also a big problem in practice. It is. In addition, when the drive current to each LD is controlled by a variable resistor, there are problems of heat generation and drift in the resistor and a decrease in operation efficiency.
[0015]
Furthermore, as the knowledge obtained by the inventors of the present invention by actually making a prototype of the laser device, when exciting one or several laser rods using several tens to several hundreds of LDs, the current value of each LD is Even if it is changed, the ratio of the amount of change that affects the entire fluorescence distribution is small. Rather, it is due to the effects of time fluctuations, thermal fluctuations, ripples, detector detection fluctuations, and noise of the current value supplied from the power source to each LD. Since the fluctuation amount of fluorescence is larger, actually, even if a mechanism for controlling the drive current of each LD is provided, it does not function effectively.
[0016]
Furthermore, when all LDs are driven by a single power supply, the allowable range of LDs is due to external components such as some parts of the power supply or malfunction of the control system, incorrect operation by the user, lightning strikes, and power outages. When an excessive current exceeding the current flows, all the LDs are destroyed uniformly at the same time.
[0017]
The present invention has been made in view of the above problems, and its main purpose is to provide a highly reliable laser device that can always accurately and accurately grasp the degree of degradation of the LD in the LD-excited solid-state laser device. It is to provide. In particular, in a solid-state laser device equipped with many tens to hundreds of LDs, a highly reliable laser device capable of grasping and detecting the degree of deterioration of LD and its deteriorated portion with an accurate and simple configuration Is to provide.
[0018]
Another object of the present invention is to provide a simple method for correcting and adjusting the degree of excitation of the solid-state laser medium in accordance with the degree of deteriorated LD.
[0019]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a solid-state laser medium that absorbs excitation light and generates or amplifies light of a predetermined wavelength, and the excitation light generated and generated directly or through an optical element. In a solid-state laser device having at least a semiconductor laser light source to be introduced into the laser medium, the output mirror or the resonator disposed opposite to the solid-state laser medium in the laser resonator constituting the solid-state laser device and the end face of the solid-state laser medium A fluorescence detecting means for detecting the amount of fluorescence generated from the solid-state laser medium at a position near the optical axis of the laser oscillation light generated in the resonator between the resonator mirror and at a position not blocking the optical axis; The fluorescence detection means is an optical means disposed in the vicinity of the optical axis of the laser oscillation light and at a position not blocking the optical axis, and a light detection for detecting the fluorescence guided to the optical means. From now, by comparing the amount with a predetermined value or previously measured values of fluorescence emitted from the solid-state laser medium that has been detected by the fluorescence detection means, the deterioration condition of the semiconductor laser light source of Diagnosis I do Is.
[0020]
The LD deterioration detection in the present invention is to measure the amount of fluorescence emitted from the laser medium, not the laser oscillation light. Since the amount of fluorescence is proportional to the amount of excitation light absorbed in the laser medium, the effect and information of the change in the amount of absorption due to the change in wavelength are also included. In particular, in the case of LD, the wavelength varies depending on the operating temperature. Since it changes greatly, it is possible to know the state of excitation and the state of wavelength change due to degradation of the LD more accurately than simply measuring the amount of excitation light emitted from the LD.
[0021]
In addition, the amount of light of fluorescence is not affected at all by the misalignment or dirt of the resonator mirror. Although the laser medium itself is deteriorated or damaged, the coating film becomes dirty, etc., but the degree is much smaller than the change of the laser oscillation light. This is because fluorescence is emitted from the entire laser medium irradiated with excitation light, and is less susceptible to local changes than laser oscillation light.
[0022]
However, unlike laser light, fluorescence has weak directivity, and when generated, it spreads and dissipates quickly while propagating. Therefore, it is desirable that the detection be performed as close to the laser medium as possible. The outer periphery of the solid-state laser medium is usually covered with a metal or the like to block the fluorescence, but the laser medium is optically exposed near the optical axis of the laser oscillation light, and the fluorescence can always be observed. However, even in the vicinity of the optical axis, the fluorescence is reflected by the mirror of the resonator outside the resonator, so it is desirable to measure within the laser resonator.
[0023]
Here, when measuring the amount of fluorescence in the resonator, the optical measuring instrument for measurement or the optical means for guiding the fluorescence to it, or the photodetector itself blocks the optical axis of the laser oscillation light. Since the laser oscillation itself is hindered, it is necessary to make it close enough not to block the optical axis in order to always detect the amount of fluorescence in the operating state.
[0024]
The inventor of the present application has actually obtained a prototype of a laser device and found experimentally that the excitation distribution of the excitation light in the laser medium is determined by determining the mechanical position configuration of the LD and the laser medium. Alternatively, it is only necessary to detect the relative value, and it is not necessary to detect the excitation distribution itself with a CCD camera. Further, if the amount of fluorescence is measured, the efficiency of excitation can be understood. It was found that the state was always kept constant. Therefore, it is not necessary to detect the amount of fluorescence on the optical axis of the laser beam, and it may be detected at a location far enough not to block the optical axis of the laser beam by utilizing the fact that the spread is larger than that of the laser beam. Moreover, since the ratio with the whole fluorescence amount is always kept constant by always measuring at the same position, the entire state of excitation can be accurately known.
[0025]
In the present invention, the excitation light may be introduced from a direction substantially orthogonal to the optical axis of the laser oscillation light.
[0026]
When irradiating excitation light from many LDs with a solid-state laser medium, the optical axis of the excitation light is arranged perpendicular to the optical axis of the laser oscillation light in the solid-state laser medium and along the optical axis of the oscillation light The so-called side excitation method is effective. In the present invention, the excitation light from the LD is not directly measured, but the amount of fluorescence from the solid laser medium is measured. Measurement is possible without depending on the excitation method, and the present invention can be applied even when the optical axis of the excitation light is set perpendicular to the optical axis of the laser oscillation light in the solid-state laser medium.
[0027]
In the present invention, the optical means includes a mirror that reflects the fluorescence emitted from the solid-state laser medium, and the fluorescence reflected by the mirror propagates in space and is disposed at a predetermined position. It can be set as the structure which injects into the said photodetector.
[0028]
When the photodetector is directly brought close to the laser oscillation optical path in the laser resonator, the photodetector may not be brought close due to the shape and size of the photodetector, or the installation position may be restricted. Therefore, the photodetector is installed at a position away from the optical axis of the laser oscillation light, the fluorescence from the laser medium is irradiated on the optical axis of the laser oscillation light, and the irradiated fluorescence is reflected toward the photodetector. By providing the means, fluorescence can be detected without bringing the direct photodetector close to the laser oscillation optical path.
[0029]
In the present invention, the optical means includes a medium transparent at the wavelength of the fluorescence, and the fluorescence incident from one end of the medium propagates through the medium and is disposed at the other end. It can also be set as the structure which injects into a photodetector.
[0030]
Since fluorescence is weak in directivity, when it is spatially propagated to a photodetector installed at a position distant from the vicinity of the laser oscillation optical path, it may spread rapidly and a sufficient amount of light may not be obtained for detection. Therefore, use a transparent medium at the wavelength of the fluorescence, place a part of the medium close to the laser oscillation optical path, and arrange a photodetector to receive the fluorescence propagated in the medium in another part. Thus, the fluorescence is confined in the medium and propagated so that the fluorescence does not diffuse or dissipate significantly until it reaches the photodetector. At this time, the portion of the medium that is brought close to the laser oscillation optical path can be easily inserted into or brought close to the laser optical path in the narrow laser resonator by processing it thinly or thinly. Furthermore, the shape of the part of the medium that is close to the laser oscillation optical path is introduced into the medium efficiently, and the surface of the medium is processed so that it efficiently propagates to the photodetector, or the surface is coated with a predetermined reflectivity. May be.
[0031]
Also, in the present invention, the optical means is formed so as to surround the periphery of the optical axis in a part of the optical path of the laser oscillation light, and the fluorescence incident from the end of the opening provided in the optical means. However, it can also be set as the structure guide | induced to the said photodetector arrange | positioned in the predetermined position of an outer peripheral side edge part. By disposing a transparent medium at the fluorescence wavelength so as to surround the periphery of the optical axis, even weak fluorescence can be effectively collected, taken out and detected.
[0032]
Further, in the present invention, the opening may be set smaller than the diameter of the laser medium. Enclose the medium sufficiently close to the oscillation optical axis in the laser resonator, and simultaneously control the oscillation mode of the laser oscillation light and separate the return light from outside the resonator by detecting the fluorescence. Can do. For example, Japanese Patent Application No. 10-253116 describes a non-absorbing circular aperture that is arranged on the laser beam path and separates the main beam and the stray light component of the laser beam. By disposing a photodetector in the vicinity of the light, it is possible to simultaneously detect fluorescence propagating through the aperture.
[0033]
In the present invention, the transparent medium is preferably formed using glass as a base material. If glass is used as a base material, the shape can be easily processed at a low cost, and the inside can be propagated to a photodetector without absorption of fluorescence.
[0034]
Moreover, in this invention, it can also be set as the structure provided with the filter which selectively attenuates the light of the wavelength of the said excitation light on the optical path of the said fluorescence which reaches the said photodetector.
[0035]
Depending on the form of excitation, there is a possibility that excitation light will be mixed into the light receiving surface for detecting fluorescence emitted from the solid-state laser medium at the same time. When the laser oscillation optical axis and the optical axis of the excitation light are parallel, a large amount of excitation light that has not been absorbed in the laser medium escapes out of the laser medium, and simultaneously with the fluorescence from the laser medium, There is a possibility of mixing.
[0036]
In this case, for example, when the wavelength of the excitation light changes and deviates from the absorption wavelength of the laser medium, the excitation light is externally absorbed due to a decrease in absorption in the solid-state laser medium, although the amount of fluorescence from the laser medium decreases. As a whole, the amount of light that leaks to the light receiving surface of the photodetector greatly changes depending on the sum of the amounts of both, and is detected in an increased manner. Therefore, the correct information that the fluorescence itself has decreased cannot be transmitted. Therefore, by providing a filter that selectively attenuates the light having the wavelength of the excitation light on the optical path where the fluorescence reaches the light receiving surface of the photodetector, only the fluorescence can be selectively received.
[0037]
Further, in the present invention, a wavelength of a fluorescence emission line spectrum that is not used for laser oscillation among the fluorescence emitted from the solid-state laser medium is selectively transmitted on the fluorescence optical path reaching the photodetector. It can also be set as the structure provided with a filter.
[0038]
When oscillation of the solid-state laser device starts, the light receiving surface of the photodetector that detects the reflected light or guided light near the optical axis, or reflected light from that position, may not only emit fluorescence but also very strong oscillating light depending on the installation position. When scattered light is irradiated and the output of the detector is saturated or the gain of the signal amplifier is lowered to avoid saturation, the fluorescence intensity before oscillation may not be measured with sufficient accuracy. Furthermore, when the oscillation light incident on the photodetector is very strong, the photodetector itself may be destroyed or the performance may be deteriorated.
[0039]
Therefore, by utilizing the fact that the fluorescence emitted from the solid-state laser medium originally has a spread, a detector that transmits only the wavelength of the spectrum that is not used for laser oscillation is provided, so that even if the laser medium oscillates, the detector Since the amount of fluorescence incident on the light does not increase significantly, the photodetector will not be saturated or destroyed.
[0040]
Further, in the present invention, the semiconductor laser light source includes a plurality of semiconductor laser elements, a power source that drives the plurality of semiconductor laser elements into a predetermined number of groups, and a control unit that controls a driving current of the power source. The drive current for each group can be adjusted by the control means in accordance with the intensity of the fluorescence detected by the photodetector.
[0041]
As described in the above conventional example, when a large number of LDs are used simultaneously for excitation in a solid-state laser device, several to several tens of LDs are electrically connected in series as one group. Although it is common to drive, solid-state lasers when not only driving in groups but also configuring an electrical circuit so that each unit can operate independently for each group power supply and driving each independently By measuring the amount of fluorescence from the medium, it is possible to individually detect and control the operating conditions such as the output and wavelength of individual LDs or LDs within a group. Can be identified.
[0042]
In addition, by exchanging only the failed LD and the minimum number of group LDs including it, the laser device can be restored without exchanging other normal LDs and all the included LDs to the normal group LDs. Therefore, the replacement and maintenance work of the LD is greatly facilitated, and the cost of parts such as the LD at the time of replacement can be reduced because the LD to be replaced may be the minimum necessary.
[0043]
Furthermore, the intensity of the fluorescence generated from the solid-state laser medium detected at the time of individually driving the electric circuit of each LD or group of LDs not only when the LD fails but also when it deteriorates slightly. By providing a control circuit that changes the drive current of each LD light source or its group according to the above, it is possible to always return the excitation state to the solid laser medium to a constant state or an initially set stable state. I can do it. In addition, differences in the absorption efficiency of excitation light caused by variations in the individual output and oscillation wavelength inherent in an LD can be minimized by practically controlling the drive current from the fluorescence intensity at the time of excitation of the LD. It is possible to correct within the range.
[0044]
In addition, it is not necessary to control the drive current of each LD independently, and a circuit configuration in which up to about 20 single LDs can be driven by a single power source as a group, and individual LDs can be driven individually. Don't do it. As a result, a small and highly reliable power supply can be configured, and even if there is a defect in the electronic components of the power supply, damage to the LD caused by the failure can be minimized.
[0045]
The present invention also provides a method for diagnosing the deterioration state of the semiconductor laser light source by the laser device as well as the semiconductor laser pumped solid laser device having the above configuration.
[0046]
DETAILED DESCRIPTION OF THE INVENTION
In a preferred embodiment of the semiconductor laser excitation solid-state laser device according to the present invention, the laser rod, the semiconductor laser element that generates excitation light, and the vicinity of the laser optical axis in the laser resonator and does not block the optical axis. At least optical means such as a reflection mirror and an optical waveguide medium provided at a position and a photodetector for detecting fluorescence, and the amount of fluorescence generated from the solid-state laser medium is detected by the light detection means, and the amount of fluorescence Is compared with a predetermined value or a previously measured value to constantly diagnose the deterioration status of the semiconductor laser light source.
[0047]
【Example】
In order to describe the above-described embodiment of the present invention in more detail, examples of the present invention will be described with reference to the drawings.
[0048]
[Example 1]
First, a semiconductor laser excitation solid-state laser device according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram schematically showing the structure of an LD-pumped solid-state laser device according to a first embodiment of the present invention, which irradiates LD excitation light along a laser oscillation optical axis in a laser medium. In the configuration of so-called end face excitation, the state of a cross section in the direction along the optical axis direction of the laser oscillation light is shown.
[0049]
As shown in FIG. 1, the excitation light 4 (wavelength 808 nm) emitted from a plurality of stacked semiconductor laser elements 2 (for example, a stack of five elements with an output of 40 W and a light emission width of 1 cm) passes through a condensing optical system 3 to form a cylindrical shape. The Nd: YAG laser rod 1 (for example, Nd concentration 1.0% at, rod diameter 3 cm, length 5 cm) is irradiated into the laser rod 1 through the end face 1a. On the opposite end face 1b of the laser rod 1, for example, a dielectric multilayer film having a reflectance of 95% or more with respect to the excitation light 808nm and 0.2% or less with respect to the laser oscillation wavelength 1064nm is formed. The excitation light 4 that has not been absorbed by the laser rod 1 is again reflected inside the laser rod 1 by the end face 1b.
[0050]
The solid-state laser oscillator of this embodiment is disposed with a reflective film coated so as to resonate at the end face 8a of the output mirror 8 (for example, concave radius of curvature 1 m) provided facing the end face 1a on which the excitation light of the laser rod is incident. The optical axis 5 of the laser oscillation light is formed. Specifically, for example, a dielectric multilayer film having a reflectance of 95% or more with respect to the excitation light 808 nm and a reflectance of 99% or more with respect to the laser oscillation wavelength 1064 nm is formed on the end face 1a, and the end face 8a is provided with the end face 8a. A dielectric multilayer film having a reflectivity of 90% with respect to the laser oscillation wavelength of 1064 nm is formed.
[0051]
On the other hand, the semiconductor photodetector 7 using Si or the like as a base material is installed in the vicinity of the optical axis 5 in the resonator and at a position that does not block the optical axis. The excitation light 4 irradiated from the semiconductor laser element 2 is absorbed in the laser rod 1, and fluorescence 6 is generated from the absorbed region. The fluorescence 6 diffuses in all directions, but a part of the fluorescence diffuses to the outside through the end face 1b on the resonator side of the laser rod 1 and reaches the semiconductor photodetector 7 as shown in FIG.
[0052]
Since the fluorescence 6 spreads uniformly in all directions from the absorbed region, if the position of the laser rod 1 or the semiconductor photodetector 7 does not change, the change in the amount of fluorescence detected by the semiconductor photodetector 7 is The total amount of fluorescence 6 generated from the entire laser rod 1, that is, the amount of absorption of the excitation light 4 is approximately proportional. The most typical cause of the decrease in the amount of absorption of the pumping light 4 is a decrease in pumping light output due to deterioration of the semiconductor laser element. Although there are few, there are dirt and breakage of condensing optical system 3, damage of laser rod 1, etc.
[0053]
As a specific procedure for detecting deterioration of the semiconductor laser element 2, the semiconductor photodetector 7 detects the amount of fluorescence when the semiconductor laser element 2 is driven with a specific drive current in an initial state where the semiconductor laser element 2 is not deteriorated. The semiconductor laser device 2 is driven with the same drive current after a lapse of a certain time or as necessary, and the deterioration state of the semiconductor laser device 2 is grasped by comparing with the fluorescence intensity detected at that time. I can do it.
[0054]
The driving current of the semiconductor laser element 2 at this time is advantageously selected to be lower than the driving current value at which the solid-state laser oscillates. Of course, it is possible to detect the amount of fluorescence even when the solid-state laser is oscillating, but in the state where the solid-state laser oscillates, it may not be possible to judge the degree of absorption of the excitation light simply by the amount of fluorescence. come. This is because when the solid-state laser oscillates, the absorbed excitation light energy is also consumed as the oscillation light. For example, if there is a failure in the solid-state laser resonator such as mirror contamination or misalignment, the absorbed excitation energy Although the rate of conversion to laser light is reduced and instead emitted as fluorescence, the amount of fluorescence detected increases, but this does not reflect the state of the excitation light. If the driving current of the semiconductor laser element 2 is selected to be lower than the driving current value oscillated by the solid-state laser, almost all of the energy absorbed in the laser rod 1 is converted into the fluorescence 6. It can be determined that the degree of is always proportional.
[0055]
As will be described later, when the semiconductor laser element 2 or a group of the semiconductor laser elements 2 is configured to be able to be driven by a plurality of independent power sources or independently, and when they are driven alone, In the case where the solid-state laser device excited by is not oscillated, each of the semiconductor laser elements 2 or a group thereof is driven independently, set to a specific current value, and the fluorescence intensity is measured. The deterioration status of the semiconductor laser element 2 or its group can be grasped independently.
[0056]
[Example 2]
Next, a semiconductor laser excitation solid-state laser device according to a second embodiment of the present invention will be described with reference to FIG. 2 and FIG. FIG. 2 is a diagram schematically showing the structure of the LD-pumped solid state laser device according to the second embodiment. In the configuration in which the pumping light of the LD is irradiated along the laser oscillation optical axis of the laser medium, The state of the cross section of the direction along the optical axis direction of the laser oscillation light is shown. FIG. 13D is a cross-sectional view showing another configuration of the mirror that reflects fluorescence.
[0057]
As shown in FIG. 2, a plurality of semiconductor laser elements 20a to 20h (each having an output of 40 W) are arranged along the longitudinal direction of the Nd: YAG laser rod 10 (for example, Nd concentration 0.7% at, rod diameter 5 cm, length 10 cm). The excitation light 40a to 40h (wavelength 809 nm) emitted therefrom is shaped through the optical systems 30a to 30h and irradiated to the laser rod 10.
[0058]
The solid-state laser resonator includes two resonator mirrors 80 and 81. End faces 80a and 81a facing the laser rods 10 have dielectric properties having a specific reflectivity with respect to the oscillation light (wavelength 1064 nm) of the solid-state laser. A body multilayer film is formed. Specifically, for example, a highly reflective film of 99% or more with respect to a wavelength of 1064 nm is formed on the end face 80a, and a partially reflective film of 80% is also formed on the 81a. The two mirrors 80 and 81 and the solid laser rod 10 form a laser oscillation optical axis indicated by 50 in the figure. For example, an antireflection film having a reflectance of 0.2% or less with respect to a wavelength of 1064 nm is formed on the end faces 10 a and 10 b where the laser optical axis 50 and the laser rod 10 are in contact with each other so as not to reflect and disperse the solid laser oscillation light. Yes.
[0059]
In the vicinity of the optical axis 50 in the laser resonator and at a position where the optical axis is not blocked, for example, a reflection mirror 71 having a reflectivity of 97% with respect to a wavelength of 1064 nm is disposed and emitted from the laser rod 10. The angle is adjusted so that the fluorescence 60 thus reflected is reflected toward the semiconductor photodetector 70. As a mirror that reflects the fluorescence 60, a parabolic mirror 96 as shown in FIG. 13 (d) can be used. In this case, the apparatus is a large scale, but the fluorescent light 60 in a wide range can be efficiently semiconductorized. The light can be condensed on the light detection unit 70 and is suitable for a system that detects the fluorescence 60 with high sensitivity.
[0060]
[Example 3]
Next, a semiconductor laser excitation solid-state laser device according to a third embodiment of the present invention will be described with reference to FIG. FIG. 3 is a diagram schematically showing the structure of an LD-excited solid-state laser device according to the third embodiment. In the configuration in which the excitation light of the LD is irradiated along the laser oscillation optical axis of the laser medium, The state of the cross section of the direction along the optical axis direction of the laser oscillation light is shown.
[0061]
As shown in FIG. 3, a plurality of semiconductors surround the laser rod 10 along the side surface and the longitudinal direction of the Nd: YAG laser rod 10 (for example, Nd concentration 0.7% at, rod diameter 5 cm, length 10 cm). Laser elements 20a to 20h are arranged, and excitation lights 40a to 40h (wavelength 809 nm) emitted therefrom are shaped through the optical systems 30a to 30h and irradiated to the laser rod 10.
[0062]
The solid-state laser resonator includes two resonator mirrors 80 and 81. End faces 80a and 81a facing the laser rods 10 have dielectric properties having a specific reflectivity with respect to the oscillation light (wavelength 1064 nm) of the solid-state laser. A body multilayer film is formed. Specifically, for example, a highly reflective film of 99% or more with respect to a wavelength of 1064 nm is formed on the end face 80a, and a partially reflective film of 80% is also formed on the 81a. The two mirrors 80 and 81 and the solid laser rod 10 form a laser oscillation optical axis indicated by 50 in the figure. Further, for example, an antireflection film having a reflectance of 0.2% or less with respect to a wavelength of 1064 nm is formed on the end faces 10a and 10b where the laser optical axis and the laser rod 10 are in contact so as not to reflect and disperse the solid laser oscillation light. .
[0063]
A medium 72 (for example, quartz glass) that is transparent to a wavelength of 1064 nm is disposed in the vicinity of the optical axis 50 in the laser resonator and at a position that does not block the optical axis, and fluorescence emitted from the laser rod 10. The angle is adjusted to reflect 60 toward the semiconductor photodetector 70. Specifically, the fluorescence 60 emitted from the laser rod 10 passes through the surface 72a of the optical waveguide medium 72 facing the laser rod 10, and is reflected by the surface 72b having an angle of about 45 degrees with respect to the fluorescence 60 that has traveled straight. Then, the light propagates through the optical waveguide medium 72, is emitted from the surface 72c, and reaches the light receiving surface of the semiconductor photodetector 70 disposed close to the surface 72c.
[0064]
By detecting the fluorescence 60 through the transparent optical waveguide medium 72 in this way, it is not necessary to bring the light receiving surface of the semiconductor photodetector 70 directly close to the optical path of the laser, and thus the degree of freedom of arrangement of the semiconductor photodetector 70. For example, even when the distance between the laser rod 10 and the resonator mirror 81 is narrow and it is difficult to insert the semiconductor photodetector 70, the fluorescent light 60 can be efficiently transferred to the semiconductor photodetector 70 by inserting a small medium 72. Can be detected.
[0065]
[Example 4]
Next, a semiconductor laser excitation solid-state laser device according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 4 is a diagram schematically showing the structure of an LD-pumped solid-state laser device according to the fourth embodiment. In the configuration in which the pumping light of the LD is irradiated along the laser oscillation optical axis of the laser medium, The state of the cross section of the direction along the optical axis direction of the laser oscillation light is shown.
[0066]
As shown in FIG. 4, a plurality of semiconductor laser elements 20a to 20d are arranged along the longitudinal direction of the rhombic Nd: YAG laser slab 15 (for example, Nd concentration 0.7% at, slab width 5 cm, length 10 cm). Excitation light 40a to 40d (wavelength 809 nm) emitted therefrom is shaped through the optical systems 30a to 30d and irradiated to the laser crystal.
[0067]
The solid-state laser resonator includes two resonator mirrors 80 and 81. The end faces 80a and 81a facing the solid-state laser slab 15 have, for example, specific reflection with respect to the oscillation light (wavelength 1064 nm) of the solid-state laser. A dielectric multilayer film having a refractive index is formed. Specifically, for example, a highly reflective film of 99% or more with respect to a wavelength of 1064 nm is formed on the end face 80a, and a partially reflective film of 80% is also formed on the 81a. These two mirrors 80 and 81 and the solid-state laser slab 15 form a zigzag laser oscillation optical axis 51 shown in the drawing. The laser oscillation light passes through the end faces 15a and 15b inclined at the Brewster angle with respect to the optical axis, and proceeds while being totally reflected by the end face 15d excited by the semiconductor laser element in the slab and the facing 15c.
[0068]
A medium 72 that is transparent to a wavelength of 1064 nm is disposed in the vicinity of the optical axis 51 in the laser resonator and at a position that does not block the optical axis, and the fluorescence 60 emitted from the solid-state laser slab 15 is converted into the semiconductor light. The angle is adjusted to reflect toward the detector 70.
[0069]
[Example 5]
Next, a semiconductor laser excitation solid-state laser device according to a fifth embodiment of the present invention will be described with reference to FIGS. 5, 13A to 13C, and FIG. FIG. 5 is a diagram schematically showing the structure of an LD-pumped solid-state laser device according to the fifth embodiment. In the configuration in which the pumping light of the LD is irradiated along the laser oscillation optical axis of the laser medium, The state of the cross section of the direction along the optical axis direction of the laser oscillation light is shown. FIGS. 13A to 13C are diagrams schematically showing the detailed structure and variations of the optical waveguide medium, and FIG. 14 schematically shows another structure of the semiconductor laser pumped solid-state laser device. It is a figure.
[0070]
As shown in FIG. 5, a plurality of Nd: YAG laser rods 10 (for example, Nd concentration 0.7% at, rod diameter 5 cm, length 10 cm) are arranged so as to surround the laser rod 10 along the side surface and the longitudinal direction. Semiconductor laser elements 20a to 20h are disposed, and excitation lights 40a to 40h (wavelength 808 nm) emitted therefrom are shaped through the optical systems 30a to 30h and irradiated to the laser rod 10.
[0071]
The solid-state laser resonator includes two resonator mirrors 80 and 81. End faces 80a and 81a facing the laser rods 10 have dielectric properties having a specific reflectivity with respect to the oscillation light (wavelength 1064 nm) of the solid-state laser. A body multilayer film is formed. Specifically, for example, a highly reflective film of 99% or more with respect to a wavelength of 1064 nm is formed on the end face 80a, and a partially reflective film of 80% is also formed on the 81a. The two mirrors 80 and 81 and the solid laser rod 10 form a laser oscillation optical axis indicated by 50 in the figure. Further, an antireflection film having a reflectance of 0.2% or less with respect to a wavelength of 1064 nm is formed on the end faces 10a and 10b where the laser optical axis and the laser rod 10 are in contact so as not to reflect and disperse the solid laser oscillation light.
[0072]
A medium 73 transparent to a wavelength of 1064 nm is disposed in the vicinity of the optical axis 50 in the laser resonator and at a position where the optical axis is not blocked. The medium 73 surrounds the optical axis 50 and has a rotationally symmetric shape around the optical axis, and the semiconductor photodetector 70 is close to the outside of the side surface. As shown in the figure, a triangular protrusion is formed on the surface of the medium 73 facing the optical axis, and the fluorescence 60 emitted from the laser rod 10 is introduced into the medium 73 through the surface 73a and reflected internally. Then, it propagates outward and finally reaches the light receiving surface of the semiconductor photodetector 70.
[0073]
More specifically, as shown in FIG. 13A, the optical waveguide medium 73 is formed in a disk shape having an opening in the central portion through which the laser light 90 passes, and has a predetermined inclination angle in the vicinity of the opening. A fluorescent incident end face 73a is provided, and a total reflection film 93 made of a metal, a dielectric film or the like is provided in a region other than the semiconductor photodetector 70 on the outer periphery, and the fluorescence 60 incident from the end face 73a is a medium 73. , And is reflected by the total reflection film 93 at the outer peripheral portion and finally enters the semiconductor photodetector 70.
[0074]
The shape of the optical waveguide medium is not limited to a disc shape, and may be a polygonal shape, an elliptical shape, or the like. For example, in the case of the trapezoid shown in FIG. 13B, the fluorescence 60 incident from the fluorescence incident end face 94a propagates toward the outer periphery of the optical waveguide medium 93, and the outer periphery other than the side where the semiconductor photodetector 70 is disposed. Then, the light is reflected by the total reflection film 93 provided on the semiconductor light detector 70 and finally enters the semiconductor photodetector 70. 13C, the center of the opening of the optical waveguide medium 95 and the laser optical axis 50 are arranged at the first focal point of the ellipse, and the semiconductor photodetector 70 is arranged at the second focal point. By doing so, all the fluorescence 60 reflected by the total reflection film 93 can be detected by the semiconductor photodetector 70. Further, in the above structure, the reflection of the fluorescence 60 can be suppressed by providing the non-reflective film 97 on the surface of the optical waveguide medium facing the semiconductor photodetector 70, and the fluorescence 60 can be efficiently guided to the semiconductor photodetector 70. Become.
[0075]
By arranging the transparent medium 73 so as to surround the periphery of the optical axis in this way, the amount of fluorescence 60 that can be introduced into the medium 73 is increased, and the amount of fluorescence 60 reaching the light receiving surface of the semiconductor photodetector 70 is increased. I can do it. In addition, since it is not necessary to bring the light receiving surface of the semiconductor photodetector 70 close to the optical path of the laser directly, the degree of freedom of arrangement of the semiconductor photodetector 70 is high. Even when it is difficult to insert the detector 70, the fluorescence 60 can be guided to the semiconductor photodetector 70 and detected by inserting the thin medium 73.
[0076]
As shown in FIG. 14, a plurality of semiconductor photodetectors 70 may be formed side by side so as to surround the disk-shaped medium 73, and by comparing the outputs from the plurality of semiconductor photodetectors 70. , The axis of laser emission Symmetry In addition, it is also possible to specify a detailed part of deterioration.
[0077]
[Example 6]
Next, a semiconductor laser excitation solid-state laser device according to a sixth example of the present invention will be described with reference to FIG. FIG. 6 is a diagram schematically showing the structure of an LD-pumped solid state laser device according to the sixth embodiment. In the configuration in which the LD excitation light is irradiated along the laser oscillation optical axis of the laser medium, The state of the cross section of the direction along the optical axis direction of the laser oscillation light is shown.
[0078]
As shown in FIG. 6, a plurality of semiconductors surround the laser rod 10 along the side surface and the longitudinal direction of the Nd: YAG laser rod 10 (for example, Nd concentration 0.7% at, rod diameter 5 cm, length 10 cm). Laser elements 20a to 20h are arranged, and excitation lights 40a to 40h (wavelength 808 nm) emitted therefrom are shaped through the optical systems 30a to 30h and irradiated to the laser rod.
[0079]
The solid-state laser resonator includes two resonator mirrors 80 and 81. End faces 80a and 81a facing the laser rods have a dielectric having a specific reflectivity with respect to the oscillation light (wavelength 1064 nm) of the solid-state laser. A multilayer film is formed. Specifically, for example, a highly reflective film of 99% or more with respect to a wavelength of 1064 nm is formed on the end face 80a, and a partially reflective film of 80% is also formed on the 81a. The two mirrors 80 and 81 and the solid laser rod 10 form a laser oscillation optical axis indicated by 50 in the figure. For example, an antireflection film having a reflectance of 0.2% or less with respect to a wavelength of 1064 nm is formed on the end faces 10 a and 10 b where the laser optical axis 50 and the laser rod 10 are in contact with each other so as not to reflect and disperse the solid laser oscillation light. Yes.
[0080]
A medium 74 that is transparent to a wavelength of 1064 nm is disposed in the vicinity of the optical axis 50 in the laser resonator and at a position that does not block the optical axis. The medium 74 has a rotationally symmetric shape around the optical axis so as to surround the optical axis 50, and the semiconductor photodetector 70 is close to the outside. As shown in the figure, a triangular protrusion is formed on the surface of the medium 74 facing the optical axis, and the fluorescence 60 emitted from the laser rod 10 is diffracted or reflected through the surface 74 a and propagates into the medium 74. Finally, it reaches the light receiving surface of the semiconductor photodetector 70.
[0081]
By disposing the transparent medium 74 so as to surround the periphery of the optical axis in this way, the amount of fluorescence 60 that can be introduced into the medium is increased, and the amount of fluorescence 60 that reaches the light receiving surface of the semiconductor photodetector 70 is increased. I can do it. Further, since it is not necessary to bring the light receiving surface of the semiconductor photodetector 70 close to the optical path of the laser directly, the degree of freedom of arrangement of the semiconductor photodetector 70 is high. For example, the distance between the laser rod 10 and the resonator mirror 81 is narrow and the semiconductor light Even when it is difficult to insert the detector 70, the fluorescence 60 can be detected by inserting the thin medium 74.
[0082]
Further, the diameter of the hole through which the optical axis of the medium 74 passes is about 3.5 mm, which is set smaller than the outer diameter of the laser rod 10. For this reason, at the time of laser oscillation, a component having a large beam divergence angle or a wide beam diameter and a poor beam quality is subjected to a large optical loss when passing through the medium 74 and is finally emitted from the mirror 81 because the oscillation is inhibited. The quality of the laser beam 90 can be improved. Improvement of the laser beam quality can be realized simultaneously with the detection of the fluorescence intensity.
[0083]
[Example 7]
Next, a semiconductor laser excitation solid-state laser device according to a seventh embodiment of the present invention is described with reference to FIG. FIG. 7 is a diagram schematically showing the structure of an LD-pumped solid-state laser device according to the seventh embodiment. In the configuration in which the pumping light of the LD is irradiated along the laser oscillation optical axis of the laser medium, The state of the cross section of the direction along the optical axis direction of the laser oscillation light is shown.
[0084]
As shown in FIG. 7, a plurality of semiconductors surround the laser rod 10 along the side surface and the longitudinal direction of the Nd: YAG laser rod 10 (for example, Nd concentration 0.7% at, rod diameter 5 cm, length 10 cm). Laser elements 20a to 20h are arranged, and excitation lights 40a to 40h (wavelength 808 nm) emitted therefrom are shaped through the optical systems 30a to 30h and irradiated to the laser rod 10.
[0085]
The solid-state laser resonator includes two resonator mirrors 80 and 81, and end surfaces 80a and 81a facing the laser rods have dielectric properties having a specific reflectivity with respect to the oscillation light (wavelength 1064 nm) of the solid-state laser. A body multilayer film is formed. Specifically, for example, a highly reflective film of 99% or more with respect to a wavelength of 1064 nm is formed on the end face 80a, and a partially reflective film of 80% is also formed on the 81a. The two mirrors 80 and 81 and the solid laser rod 10 form a laser oscillation optical axis indicated by 50 in the figure. Further, for example, an antireflection film having a reflectance of 0.2% or less with respect to a wavelength of 1064 nm is formed on the end faces 10a and 10b where the laser optical axis 50 and the laser rod 10 are in contact with each other so as not to reflect and disperse the solid laser oscillation light. ing.
[0086]
Media 72 and 74 transparent to a wavelength of 1064 nm are disposed in the vicinity of the optical axis 50 in the laser resonator and close to the mirrors 80 and 81 at positions where the optical axis is not blocked. The medium 72 is disposed so that the fluorescence 60a emitted from the end face 10a of the laser rod 10 propagates in the medium and is guided to the adjacent photodetector 70a, while the medium 74 surrounds the periphery of the optical axis 50. Thus, it has a rotationally symmetric shape around the optical axis, and the semiconductor photodetector 70b is close to the outside. As shown in the figure, a triangular protrusion is formed on the surface of the medium 74 facing the optical axis, and the fluorescent light 60b emitted from the laser rod 10 is diffracted or reflected by the surface and propagated into the medium 74. Finally, it reaches the light receiving surface of the semiconductor photodetector 70b.
[0087]
When the laser rod 10 is long and the number of arrangements of semiconductor laser elements increases, the fluorescence of the LD or the excitation region of the laser rod 10 that is farther from the semiconductor photodetector is dissipated because the fluorescence has less directivity. However, by disposing the semiconductor photodetectors on both end surfaces with the laser rod 10 interposed therebetween, information on the semiconductor laser element or the excitation region far from one of the detectors can be obtained more accurately.
[0088]
[Example 8]
Next, a semiconductor laser pumped solid state laser device according to an eighth embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a diagram schematically showing the structure of an LD-pumped solid state laser device according to the eighth embodiment. In the configuration in which the pumping light of the LD is irradiated along the laser oscillation optical axis of the laser medium, The state of the cross section of the direction along the optical axis direction of the laser oscillation light is shown. FIG. 9 is a diagram illustrating the transmission characteristics of the excitation light blocking filter, and FIG. 10 is a diagram illustrating the transmission characteristics of the narrow-band transmission filter that extracts only the wavelength component that does not contribute to oscillation.
[0089]
As shown in FIG. 8, the excitation light 4 (wavelength 808 nm) emitted from a plurality of stacked semiconductor laser elements 2 (for example, a stack of five elements with an output of 40 W and a light emission width of 1 cm) passes through the condensing optical system 3 to form a cylindrical shape. The laser rod 1 is irradiated through the end face 1a of the Nd: YAG laser rod 1 (for example, Nd concentration 0.8% at, rod diameter 3 cm, length 5 cm).
[0090]
On the opposite end face 1b of the laser rod 1, for example, a dielectric multilayer film having a reflectance of 95% or more with respect to the excitation light 808nm and 0.2% or less with respect to the laser oscillation wavelength 1064nm is formed. The excitation light that has not been absorbed by the laser rod 1 is reflected again by the end face 1 b and returned to the laser rod 1.
[0091]
The solid-state laser oscillator of this embodiment is disposed with a reflection film coating so as to resonate at the end face 8a of the output mirror 8 provided opposite to the end face 1a on which the excitation light 4 of the laser rod 1 is incident. The optical axis 5 is formed. Specifically, for example, a dielectric multilayer film having a transmittance of 95% or more with respect to the excitation light 808 nm and a reflectance of 99% or more with respect to the laser oscillation wavelength 1064 nm is formed on the end face 1a. Similarly, a dielectric multilayer film having a reflectivity of 90% with respect to the laser oscillation wavelength of 1064 nm is formed on the end face 8a.
[0092]
A medium 72 that is transparent to a wavelength of 1064 nm is disposed in the vicinity of the optical axis 5 in the laser resonator and at a position that does not block the optical axis. The medium 72 has a rotationally symmetric shape around the optical axis so as to surround the optical axis 5, and the semiconductor photodetector 7 is close to the outside. As shown in the figure, a triangular protrusion is formed on the surface of the medium 72 facing the optical axis, and the fluorescence 6 emitted from the laser rod 1 is diffracted or reflected by the surface and propagated into the medium 72. Finally, it reaches the light receiving surface of the semiconductor photodetector 7.
[0093]
By arranging the transparent medium 73 so as to surround the periphery of the optical axis 5 in this way, the amount of fluorescence 6 that can be introduced into the medium 73 increases, and the amount of fluorescence 6 that reaches the light receiving surface of the semiconductor photodetector 7 is increased. Can be increased. Further, since it is not necessary to bring the light receiving surface of the semiconductor photodetector 7 close to the optical path of the laser directly, the degree of freedom of arrangement of the semiconductor photodetector 7 is high. For example, the distance between the laser rod 1 and the resonator mirror 8 is narrow and the semiconductor light Even when it is difficult to insert the detector 7, the fluorescence 6 can be detected by inserting the thin medium 72.
[0094]
Further, between the side surface of the medium 73 and the semiconductor photodetector 7, an excitation light blocking filter (for example, HOYA RM100) 75 that absorbs the wavelength of the excitation light 4 and transmits only the fluorescence 6 emitted from the laser rod 1. And a narrow-band transmission filter (interference filter) 76 that transmits only the wavelength component that does not contribute to laser oscillation in the fluorescence 6 is inserted, and the semiconductor photodetector 7 has a wavelength that does not contribute to laser oscillation in the fluorescence 6. Only light arrives and is detected. By providing two filters in this way, it is possible to accurately and reliably measure the amount of fluorescence generated by absorbing the excitation light, not the excitation light itself.
[0095]
FIG. 9 is a diagram showing an example of transmission characteristics of the excitation light blocking filter 75 that cuts excitation light and transmits only fluorescence. As can be seen from the figure, the transmittance is as low as less than 5% in the vicinity of the excitation light of 808 nm, and conversely, the transmittance is high in the vicinity of the fluorescence wavelength of 1064 nm. Examples of such a filter include R85 or RM100 manufactured by HOYA. Further, a dielectric multilayer film having the same permeability may be used instead of the absorption type filter.
[0096]
FIG. 10 is a diagram showing an example of the transmission characteristics of the narrow-band transmission filter 76 that extracts only the wavelength component that does not contribute to the oscillation among the fluorescent components emitted from the laser rod 1. As can be seen from the figure, only the 946 nm component of the fluorescent component is transmitted, and light in the vicinity of 1064 nm that mainly contributes to oscillation is not transmitted. Such characteristics can be easily realized by using an interference filter. Of course, a band-pass filter using a dielectric multilayer film may be used instead of the interference filter. Further, the transmission wavelength may be in the vicinity of 1310 nm, which is another emission spectrum of Nd: YAG.
[0097]
In the present embodiment, the configuration in which the excitation light blocking filter 75 and the narrow band transmission filter 76 are provided between the optical waveguide medium 73 and the semiconductor photodetector 7 is described. However, the optical waveguide medium 73 itself is light having a specific wavelength. It is also possible to have a filter function by forming a material that permeates or absorbs. It is also possible to finely divide the band of the narrow-band transmission filter 76 in the vicinity of the fluorescence wavelength and detect a shift in the fluorescence wavelength that changes according to the deterioration of the laser rod 1.
[0098]
[Example 9]
Next, a semiconductor laser excitation solid-state laser device according to a ninth embodiment of the present invention is described with reference to FIG. FIG. 11 is a diagram schematically showing the structure of an LD-pumped solid-state laser device according to the ninth embodiment, in which a plurality of LD-pumped lights are emitted along the laser oscillation optical axis of a plurality of laser media arranged in series. 2 shows a cross section in a direction along the optical axis direction of the laser oscillation light.
[0099]
As shown in FIG. 11, the side and longitudinal sides of three Nd: YAG laser rods 10, 11, and 12 (for example, Nd concentration 0.7% at, rod diameter 5 cm, each length 10 cm) arranged in the longitudinal direction. A plurality of semiconductor laser elements 20a to 20h, 21a to 21h, and 22a to 22h are arranged along the direction, and excitation lights 40a to 40h, 41a to 41h, and 42a to 42h (wavelength 808 nm) emitted therefrom. Are shaped through the optical systems 30a to 30h, 31a to 31h, and 32a to 32h, respectively, and irradiated to the laser rods 10, 11, and 12.
[0100]
The solid-state laser resonator includes two resonator mirrors 80 and 81. End faces 80a and 81a facing the laser rods have a dielectric having a specific reflectivity with respect to the oscillation light (wavelength 1064 nm) of the solid-state laser. A multilayer film is formed. Specifically, for example, a highly reflective film of 99% or more with respect to a wavelength of 1064 nm is formed on the end face 80a, and a partially reflective film of 50% is also formed on the 81a. The two mirrors 80 and 81 and the solid laser rods 10 to 12 form a laser oscillation optical axis indicated by 51 in the figure. Further, the end faces 10a to 12a and 10b to 12b where the laser optical axis 51 and the laser rods 10 to 12 are in contact have, for example, a reflectance of 0.2% or less with respect to a wavelength of 1064 nm so that solid laser oscillation light is not reflected and dissipated. An antireflection film is formed.
[0101]
Transparent media 72a to 72d with respect to the wavelength of 1064 nm are disposed in the vicinity of the optical axis 51 in the laser resonator and at positions where the optical axis is not blocked. Each medium has a rotationally symmetric shape around the optical axis so as to surround the optical axis 51, and the fluorescence 60 a to 62 a and 60 b to 62 b emitted from the end faces of the laser rods 10, 11, 12 are contained in the medium. Are arranged so as to be guided to the photodetectors 70a to 70d that are propagated close to each other. As shown in the figure, a triangular protrusion is formed on the surface of each medium facing the optical axis, and the fluorescence emitted from each laser rod is diffracted or reflected by that surface and propagates into the medium. In particular, it reaches the light receiving surface of the semiconductor photodetector.
[0102]
Specifically, the medium 72a detects the fluorescence 60a generated through the end face 10a of the laser rod 10, and the medium 72b detects the fluorescence 60b or 61a emitted through the end face 10b of the laser rod 10 or the end face 11a of the laser rod 11. The medium 72c detects the fluorescence 61b or 62a emitted through the end face 11b of the laser rod 11 or the end face 12a of the laser rod 12, and the medium 72d is arranged to detect the fluorescence 62b emitted through the end face 12b of the laser rod 12. Yes.
[0103]
When the laser rod is long and the number of semiconductor laser arrays increases, the fluorescence is less directional and the LD or the laser rod excitation region farther from the detector dissipates. By disposing the semiconductor photodetectors on both end face sides with the laser rods 10 to 12 interposed therebetween, it is possible to know the information of the LD or excitation region far from one detector more accurately.
[0104]
Further, between each of the media 72a to 72d and the semiconductor photodetectors 70a to 70d, excitation light blocking filters 75a to 75a that absorb or reflect the wavelength of the excitation light of the semiconductor laser and transmit only the fluorescence emitted from the laser rod. Narrow-band transmission filters 76a to 76d that transmit only 75d and wavelength components that do not contribute to laser oscillation in the fluorescence are inserted, and only light having a wavelength that does not contribute to laser oscillation reaches the semiconductor photodetector. Detected. By providing two filters in this way, it is possible to accurately and reliably measure the amount of fluorescence generated by absorbing the excitation light, not the excitation light itself.
[0105]
[Example 10]
Next, a semiconductor laser excitation solid-state laser device according to a tenth embodiment of the present invention will be described with reference to FIG. FIG. 12 is a diagram schematically showing the structure of an LD-pumped solid state laser device according to the tenth embodiment. In the configuration in which the pumping light of the LD is irradiated along the laser oscillation optical axis of the laser medium, The state of the cross section of the direction along the optical axis direction of the laser oscillation light is shown.
[0106]
As shown in FIG. 12, a plurality of Nd: YAG laser rods 11 and 12 (for example, Nd concentration: 1.0% at, rod diameter: 5 cm, length: 10 cm) arranged in the longitudinal direction are also plural in the longitudinal direction. Semiconductor laser elements 25a to 25h and 26a to 25h are arranged, and excitation lights 40a to 40h and 41a to 41h (wavelength 809 nm) emitted therefrom are shaped through the optical systems 30a to 30h and 31a to 31h. The laser rod is irradiated.
[0107]
The solid-state laser resonator includes two resonator mirrors 80 and 81. End faces 80a and 81a facing the laser rods have a dielectric having a specific reflectivity with respect to the oscillation light (wavelength 1064 nm) of the solid-state laser. A multilayer film is formed. Specifically, for example, a highly reflective film of 99% or more with respect to a wavelength of 1064 nm is formed on the end face 80a, and a 75% partially reflective film is formed on the 81a. The two mirrors 80 and 81 and the solid laser rods 11 and 12 form a laser oscillation optical axis indicated by 51 in the figure. Further, the end faces 11a, 11b, 12a and 12b where the laser optical axis 51 and the laser rods 11 and 12 are in contact have an antireflection film having a reflectance of 0.2% or less with respect to a wavelength of 1064 nm so as not to reflect and disperse the solid laser oscillation light. Is formed.
[0108]
Transparent media 72a to 72c with respect to a wavelength of 1064 nm are disposed in the vicinity of the optical axis 51 in the laser resonator and at positions where the optical axis is not blocked. Each of the media 72a to 72c has a rotationally symmetric shape around the optical axis so as to surround the optical axis 5, and the semiconductor photodetectors 70a to 70c are close to the outside. As shown in the figure, triangular projections are formed on the surfaces of the media 72a to 72c facing the optical axis, and the fluorescences 60a, 60b, 61a, 61b emitted from the laser rods 11, 12 are diffracted on the surfaces. Alternatively, it is reflected and propagated inside the medium, and finally reaches the light receiving surface of the semiconductor photodetector.
[0109]
When the rods are long and the number of semiconductor laser arrays increases, the fluorescence is less directional and the LD or the excitation region of the rod farther from the detector dissipates. By disposing the semiconductor photodetectors on both side surfaces with 11 and 12 in between, information on the semiconductor laser or the excitation region far from one of the detectors can be obtained more accurately.
[0110]
Further, an excitation light blocking filter that absorbs or reflects the wavelengths of the excitation light 40a to 40h and 41a to 41h and transmits only the fluorescence emitted from the laser rod is provided between the mediums 72a to 72c and the photodetectors 70a to 70c. 75a to 75c and narrowband transmission filters 76a to 76c that transmit only the wavelength component of the fluorescence that does not contribute to laser oscillation are inserted, and the semiconductor photodetectors 70a to 70c have wavelengths that do not contribute to laser oscillation of the fluorescence. Only the light of the arrival is detected. Thus, by providing two filters, the absorption state of the excitation light from the LD can be accurately measured.
[0111]
As shown in the figure, two semiconductor laser elements are connected in series and driven by independent power sources 25a to 26d. Control signals for controlling the current value from the outside are supplied to these power supplies from the interfaces 91a to 91d. Further, the interface is controlled / monitored / recorded by the host control host 92.
[0112]
Next, an example of a basic control flow will be described. In response to a command from the control host 92, a current of 25 amperes is supplied from the power source 25a to the semiconductor laser elements 20a and 20b via the interface 91a. At this time, power supplies other than the power supply 25a are inactive. Excitation lights 40a and 40b from the semiconductor laser elements 20a and 20b are shaped by the optical systems 30a and 30b, and then irradiated to the laser rod 11. The semiconductor laser light is absorbed by the laser rod 11a and emits fluorescence 60a. The fluorescence propagates to the nearest fluorescence detecting transparent medium 72a from the position where the fluorescence is generated, and after propagating through the medium 72a, the excitation light blocking filter 75a for removing the excitation light and the fluorescence component are actually lasers. After passing through the filter 76a that transmits only the component that does not contribute to oscillation, the light reaches the semiconductor photodetector 70a and is detected.
[0113]
At this time, since only the semiconductor laser elements 20a and 20b are driven, the amount of fluorescence detected by the semiconductor photodetector 70a is generated by excitation from the semiconductor laser elements 20a and 20b. Therefore, the amount of fluorescence detected is proportional to the amount of absorption of the excitation light of the semiconductor laser elements 20a and 20b, in other words, a value reflecting the total amount of output light and the wavelength of these semiconductor laser elements.
[0114]
Next, similarly, the semiconductor laser elements 20c and 20d are energized from the power supply 25b through the interface 91b according to a command from the control host 92. The fluorescent light 60b generated at this time is detected by the semiconductor photodetector 70b through the closest distance 72b. The drive current at this time must be selected to a value that does not oscillate the solid-state laser device.
[0115]
In this way, all the drive power supplies 25a to 26d are driven independently in order, and the fluorescence intensity generated at that time is detected by the nearest semiconductor photodetector and recorded in the control host 92. A specific current value, for example, 25 amperes is energized in a reference state, for example, these semiconductor laser elements are new and not deteriorated at all, and the amount of fluorescence at this time is stored in the memory of the control host 92. . Next, after a certain period of time has elapsed, or when an abnormality has occurred in the solid-state laser output, all the drive power supplies are again driven in the same manner, and the fluorescence intensity generated at that time is exactly the same by the semiconductor photodetector. To detect. By comparing these values with the original values, it is possible to individually detect the degree of deterioration of each semiconductor laser element. For example, when the amount of fluorescence decreases to 70% or less at the start of use, it may be determined that the semiconductor laser element driven by the power source has deteriorated and replaced.
[0116]
In the above embodiment, Nd: YAG is given as an example of the laser medium. However, any other lasing element such as Yb, Ho, Tm, Cr, Ti may be used, and the base material may be used. In addition, crystals such as YLF, YVO4, GGG, and GSGG may be used, and amorphous substances such as glass and ceramics may be used.
[0117]
Further, as an example of the material of the optical waveguide medium, glass is given as an example, but any material having a high transmittance with respect to excitation light may be used. In particular, if glass having a high refractive index to which lead is added is used, excitation light propagating in the waveguide plate can be efficiently propagated by total reflection. Further, as a transparent material having a high refractive index, a crystal material such as sapphire or YAG not containing a laser element may be used. In addition, the shape of the optical waveguide medium includes a disk shape with a hole, a trapezoidal shape, an elliptical shape, and a parabolic shape. However, any other shape may be used to propagate the fluorescence generated from the laser medium to the photodetector. All within the scope of the claims of this patent. Further, the shape and medium need only be those that do not weaken in the course of propagation as much as possible. Since resin such as plastic may be used, optical fiber may be used. Although the diameter of the laser rod is 5 mm in the embodiment, other diameters may be used, and the optimum diameter and length are selected according to the configuration of the required laser device. The oscillation wavelength of the LD used for excitation may be other than 808 nm, and an optimum wavelength is selected in consideration of the configuration of the laser crystal and the excitation distribution.
[0118]
As the semiconductor laser element, for example, SDL3470S manufactured by SDL of the United States can be used. Alternatively, OPC-A020-MMM-CL manufactured by Optopower of the US or TH-C1720-P manufactured by Tomson-CSF of France may be used. Further, TH-C1720-R (4) of Tomson-CSF, France, in which four semiconductor laser elements are arranged in advance in an array, may be used. The output of the semiconductor laser element may be 20 W or less for 1 cm, so it may be for 30 W or 40 W. In this case, the semiconductor laser element is used at an output less than half of the rated output, so the life of the semiconductor laser element is 3 to 9 times longer. Thus, the reliability of the solid-state laser device can be improved.
[0119]
In the above embodiment, the excitation light blocking filter that attenuates the light having the excitation light wavelength and the narrow band transmission filter that selectively transmits only the fluorescence emission line wavelength of the solid-state laser medium that does not contribute to the oscillation are used in pairs. If the excitation light does not reach the semiconductor photodetector due to the excitation configuration, the former filter may be omitted, or the filter that selectively transmits only the fluorescence emission line wavelength of the solid laser rod may be omitted. When the transmission wavelength band reaches the wavelength of the excitation light, the former filter may be omitted since the excitation light does not pass through the latter filter. An example of Si was given as the semiconductor photodetector, but Ge, GaAs, InGaAs, or other semiconductor materials may be used. A material that can be detected with the highest sensitivity is selected in accordance with the fluorescence wavelength.
[0120]
If the pumping light does not reach the semiconductor photodetector due to the pumping configuration and the solid-state laser oscillates and the light detector does not degrade the performance due to the oscillation light, omit any filter. Also good. Further, instead of this, for example, an ND filter or a diffuser plate may be inserted so as to attenuate all light so that the photodetector is not deteriorated by the oscillating light.
[0121]
【The invention's effect】
As described above, in a semiconductor laser pumped solid-state laser device that absorbs and amplifies pumping light from a semiconductor laser with a laser rod, a reflection mirror or optical waveguide is positioned in the vicinity of the optical axis in the resonator and without blocking the optical axis. By providing a medium etc. and guiding the fluorescence emitted from the laser rod to the semiconductor photodetector, the excitation state can be accurately grasped, and the state and lifetime of the excitation semiconductor laser can be measured while the laser device is in operation. Can be managed.
[0122]
In the present invention, the excitation light from the semiconductor laser is not directly measured, but the fluorescence from the laser rod is measured. Therefore, the excitation light and the excitation light are not dependent on the positional relationship between the semiconductor laser and the laser rod and the excitation method. The present invention can be applied to both a configuration in which the optical axes of the laser beams are coincident and a configuration in which the optical axes are orthogonal to each other.
[0123]
In the present invention, the semiconductor photodetector for measuring fluorescence does not have to be in the resonator or in the vicinity of the laser optical axis, and may be guided by a reflection mirror or an optical waveguide medium. Even in a narrow case, fluorescence can be detected reliably.
[0124]
In addition, the optical waveguide medium is formed in a donut shape so as to surround the periphery of the optical axis, and the opening diameter inside the optical waveguide medium is made smaller than the diameter of the laser rod, thereby suppressing oscillation of a beam having a large spread angle. In addition, the laser beam quality can be improved simultaneously with the detection of the fluorescence intensity.
[0125]
In the present invention, since an excitation light blocking filter and a narrow band transmission filter are installed in the front stage of the semiconductor photodetector, mixing of excitation light can be prevented and only fluorescence that contributes to laser oscillation can be detected. The absorption state of excitation light can be accurately measured.
[0126]
Further, according to the present invention, a plurality of semiconductor laser elements are divided into a plurality of groups, a power source for driving the semiconductor laser elements is individually provided for each group, and the power source is controlled according to a command from the host. It becomes possible to individually diagnose the deterioration state of the laser element.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing the structure of an LD-pumped solid-state laser device according to a first embodiment of the present invention.
FIG. 2 is a diagram schematically showing the structure of an LD-pumped solid state laser apparatus according to a second embodiment of the present invention.
FIG. 3 is a diagram schematically showing the structure of an LD-pumped solid state laser apparatus according to a third embodiment of the present invention.
FIG. 4 is a diagram schematically showing the structure of an LD-pumped solid state laser device according to a fourth embodiment of the present invention.
FIG. 5 is a diagram schematically showing the structure of an LD-pumped solid state laser apparatus according to a fifth embodiment of the present invention.
FIG. 6 is a diagram schematically showing a structure of an LD-pumped solid state laser apparatus according to a sixth embodiment of the present invention.
FIG. 7 is a diagram schematically showing the structure of an LD-pumped solid state laser device according to a seventh embodiment of the present invention.
FIG. 8 is a diagram schematically showing a structure of an LD-pumped solid state laser device according to an eighth embodiment of the present invention.
FIG. 9 shows the characteristics of a filter that blocks the wavelength of excitation light.
FIG. 10 shows the characteristics of a filter that transmits only the wavelength of the emission line spectrum that is not used for laser oscillation.
FIG. 11 is a diagram schematically showing the structure of an LD-pumped solid state laser apparatus according to a ninth embodiment of the present invention.
FIG. 12 is a diagram schematically showing the structure of an LD-pumped solid state laser device according to a tenth embodiment of the present invention.
FIGS. 13A and 13B are diagrams showing another structure of the LD-pumped solid-state laser device of the present invention, wherein FIGS. 13A to 13C show other structures of the optical waveguide medium, and FIG. FIG.
FIG. 14 is a diagram schematically showing another structure of an LD-pumped solid state laser device according to a fifth embodiment of the present invention.
FIG. 15 is a diagram showing a structure of a conventional LD-pumped solid-state laser device.
FIG. 16 is a diagram showing a structure of a conventional LD-pumped solid-state laser device.
[Explanation of symbols]
1 Laser rod
1a, 1b Laser rod end face
2 Semiconductor laser device
3 Condensing optical system
4 Excitation light
5 optical axes
6 Fluorescence
7 Photodetector
8 Mirror
8a Mirror end face
9 Laser light
10 Laser rod
10a, 10b Laser rod end face
15 Laser rod slab
15a, 15b Brewster cut surface
15c, 15d Total reflection end face
20a-20h, 21a-21h, 22a-22h Semiconductor laser element
25a-25d, 26a-26d DC power supply
30a-30h, 31a-31h, 32a-32h Optical system
40a-40h, 41a-41h, 42a-42h Excitation light
50 Laser optical axis
60, 60a, 60b, 61a, 61b, 62a, 62b Fluorescence
70, 70a-70d Semiconductor photodetector
71 reflection mirror
72, 72a to 72d, 73, 74, 94, 95 Optical waveguide medium
72a, 72c Low reflection coating end face
72b Total reflection end face
73a, 74a, 94a, 95a Fluorescent incident end face
75, 75a-75d Excitation light blocking filter
76, 76a-76d Narrow band transmission filter
80 Cavity mirror
80a Mirror end face
81 Cavity mirror
81a Mirror end face
90 Laser light
91a-91d interface
92 Control host device
93 Total reflection film
96 Parabolic mirror
97 Antireflective film
101 Laser rod
102-107 Excitation semiconductor laser device
117 power supply
120 Cavity mirror (total reflection)
121 Resonator mirror (partial reflection)
122-127 variable resistance
128 Folding mirror
129 condenser lens
130 CCD camera
131 Control circuit

Claims (24)

A solid-state laser medium that absorbs excitation light and generates or amplifies light of a predetermined wavelength; and a semiconductor laser light source that generates the excitation light and introduces the generated excitation light into the laser medium directly or via an optical element; In a solid-state laser device having at least
Light of laser oscillation light generated in the resonator between the solid-state laser medium in the laser resonator constituting the solid-state laser device and an output mirror or resonator mirror disposed opposite to the end face of the solid-state laser medium A fluorescence detection means for detecting the amount of fluorescence generated from the solid-state laser medium at a position near the axis and not blocking the optical axis, wherein the fluorescence detection means is located near the optical axis of the laser oscillation light and the optical axis An optical means disposed at a position not obstructed, and a photodetector for detecting the fluorescence guided to the optical means,
By comparing the amount with a predetermined value or previously measured values of fluorescence emitted from the solid-state laser medium that has been detected by the fluorescence detection means, and characterized by performing the diagnosis of the deterioration condition of the semiconductor laser light source Semiconductor laser pumped solid state laser device.   2. The semiconductor laser excitation solid-state laser device according to claim 1, wherein the excitation light is introduced from a direction substantially orthogonal to the optical axis of the laser oscillation light.   The optical means includes a mirror that reflects the fluorescence emitted from the solid-state laser medium, and the fluorescence reflected by the mirror propagates in space to the photodetector disposed at a predetermined position. 3. The semiconductor laser excitation solid-state laser device according to claim 1, wherein the semiconductor laser excitation solid-state laser device is incident.   4. The semiconductor laser pumped solid-state laser device according to claim 3, wherein the mirror is formed in a parabolic shape, and the fluorescence reflected by the mirror propagates in space and is condensed on the photodetector.   The optical means includes a medium transparent at the wavelength of the fluorescence, and the fluorescence incident from one end of the medium propagates inside the medium and enters the photodetector disposed at the other end. The semiconductor laser pumped solid-state laser device according to claim 1 or 2.   The optical means is formed so as to surround the periphery of the optical axis in a part of the optical path of the laser oscillation light, and the fluorescence incident from the end of the opening provided in the optical means is 6. The semiconductor laser excitation solid-state laser device according to claim 5, wherein the semiconductor laser excitation solid-state laser device is guided to the photodetector arranged at a predetermined position.   7. The semiconductor laser pumped solid state laser device according to claim 6, wherein the optical means has a disc shape, a polygonal shape or an elliptical shape.   8. The semiconductor laser excitation solid-state laser device according to claim 7, wherein the center of the aperture is disposed at the first focal point having the elliptical shape, and the photodetector is disposed at the second focal point. Reflecting means for reflecting the fluorescence is provided in a region other than the vicinity of the photodetector in the outer periphery of the optical means, and the fluorescence incident on the opening side end is reflected by the reflecting means and the photodetector. the semiconductor-laser-pumped solid-state laser apparatus according to any one of claims 6 to 8 is possible, characterized in that led to.   A plurality of the photodetectors are arranged over the entire outer circumference of the optical means, and by comparing the outputs of the plurality of photodetectors, the axial symmetry of the laser beam or the identification of the degraded semiconductor laser light source is identified. 8. The semiconductor laser pumped solid-state laser device according to claim 6 or 7, wherein:   11. The semiconductor laser excitation laser device according to claim 6, wherein the opening is set smaller than a diameter of the laser medium.   12. The semiconductor laser pumped solid-state laser device according to claim 5, wherein the transparent medium is formed using glass as a base material.   The transparent medium is formed of a material that selectively attenuates the light having the wavelength of the excitation light or a material that selectively transmits the wavelength of the fluorescence emission line spectrum that is not used for laser oscillation. The semiconductor laser excitation solid-state laser apparatus as described in any one of Claims 5 thru | or 12. A solid-state laser medium that absorbs excitation light and generates or amplifies light of a predetermined wavelength; and a semiconductor laser light source that generates the excitation light and introduces the generated excitation light into the laser medium directly or via an optical element; Laser oscillation light generated in the resonator between the solid-state laser medium in the laser resonator constituting the solid-state laser device and an output mirror or resonator mirror disposed opposite to the end face of the solid-state laser medium. A method for diagnosing the state of a solid-state laser device having at least fluorescence detection means provided in the vicinity of the optical axis and at a position that does not block the optical axis,
The fluorescence detection means includes an optical means disposed in the vicinity of the optical axis of the laser oscillation light and at a position not blocking the optical axis, and a photodetector for detecting the fluorescence guided to the optical means. The amount of fluorescence generated from the solid-state laser medium is detected by the fluorescence detection means, and the deterioration state of the semiconductor laser light source is determined by comparing the amount of fluorescence with a predetermined value or a value measured in advance. A method for diagnosing a semiconductor laser-pumped solid-state laser device, characterized by diagnosing.   The optical means includes a mirror that reflects the fluorescence emitted from the solid-state laser medium, and the fluorescence reflected by the mirror is spatially propagated and incident on the photodetector disposed at a predetermined position. 15. The method for diagnosing a semiconductor laser pumped solid-state laser device according to claim 14.   16. The diagnostic method of a semiconductor laser excitation solid-state laser device according to claim 15, wherein the mirror is formed in a parabolic shape, and the fluorescence reflected by the mirror is spatially propagated and condensed on the photodetector. .   The optical means includes a transparent medium at the fluorescence wavelength, and causes the fluorescence incident from one end of the medium to propagate inside the medium and enter the photodetector disposed at the other end. 15. The method for diagnosing a semiconductor laser pumped solid-state laser device according to claim 14.   The optical means is formed so as to surround the periphery of the optical axis in a part of the optical path of the laser oscillation light, and the fluorescence incident from the end of the opening provided in the optical means is 18. The method for diagnosing a semiconductor laser-pumped solid-state laser device according to claim 17, wherein the method is led to the photodetector arranged at a predetermined position.   19. The method for diagnosing a semiconductor laser pumped solid-state laser device according to claim 18, wherein the optical means has a disc shape, a polygonal shape, or an elliptical shape.   The diagnostic method of a semiconductor laser excitation solid-state laser device according to claim 19, wherein the center of the opening is arranged at the first focal point of the elliptical shape, and the photodetector is arranged at the second focal point.   Reflecting means for reflecting the fluorescence in a region other than the vicinity of the photodetector in the outer periphery of the optical means, and the fluorescence reflected by the reflecting means is reflected by the reflecting means. 21. The method for diagnosing a semiconductor laser pumped solid-state laser device according to any one of claims 18 to 20, wherein:   A plurality of the photodetectors are arranged over the entire outer circumference of the optical means, and the output of the plurality of photodetectors is compared to identify the axial symmetry of the laser light or the deteriorated semiconductor laser light source. 20. The method for diagnosing a semiconductor laser pumped solid-state laser device according to claim 18 or 19, wherein:   23. The spread angle of the laser beam is controlled by setting the opening smaller than the diameter of the laser medium and suppressing a laser beam having a large spread angle by the medium. The diagnostic method of the semiconductor laser excitation laser apparatus as described in any one.   The transparent medium is formed of a material that selectively attenuates the light having the wavelength of the excitation light or a material that selectively transmits the wavelength of the fluorescence emission line spectrum that is not used for laser oscillation. The method for diagnosing a semiconductor laser pumped solid-state laser device according to any one of claims 17 to 23.

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